code: def test_exp_save_custom_message(tmp_dir, dvc, scm):
      setup_stage(tmp_dir, dvc, scm)
  
      exp = dvc.experiments.save(message="custom commit message")
      assert (
          scm.gitpython.repo.commit(exp).message
          == "custom commit message"
      )
  
file_path: dvc/tests/func/experiments/test_save.py
imports: import pytest
  from funcy import first
  from dvc.repo.experiments.exceptions import ExperimentExistsError, InvalidArgumentError
  from dvc.repo.experiments.utils import exp_refs_by_rev
  from dvc.scm import resolve_rev
label_desc: Use image node_id 13 for calling a global function with example usage: test_exp_save_custom_message(tmp_dir, dvc, scm) without return types